End node

An end node (EN) is an APPN node that relies on the directory and route selection services of a network node to participate in an APPN network.

A VTAM® EN:

Interacts with a network node to request and receive directory and route selection services
Supports CP-CP sessions between the end node and its network node server
Can specify a preferred network node server by means of the NNSPREF start option
Can define a network node server list
Submits search requests to its network node server and obtains the session route from its server when initiating LU-LU sessions
Dynamically registers its resources with its network node server so that the resources can be found during broadcast searches
Has the NODETYPE start option set to EN (NODETYPE=EN)
Cannot activate an NCP
Does not have a subarea number defined on the HOSTSA start option
Note: If the start option, SACONNS, is set to NO, VTAM HOSTA is a pure APPN node even if HOSTA is coded.

An EN provides communication services for those resources defined within the node. An EN provides directory and session services for its own LUs only.

For directory and routing services to other nodes, an end node uses the services of its network node server. An end node can have links to several network nodes for connectivity and routing, but only one of these network nodes can be used as the network node server at any given time. A VTAM EN can register its resources in the directory services database of its network node server. This allows searches from other nodes to locate the resources on this EN because VTAM end nodes are not searched. An EN does not perform intermediate routing of sessions; it can only be the origin or destination of a session.

Both a data host and an EN primarily process applications and do not provide network services for the resources attached to them. If your data host has APPN connections and does not require subarea connections, you can migrate it to an EN. (If your data host requires subarea connections, you can migrate it to a migration data host, which is described in Migration data host.)